@@ -35,6 +35,132 @@ static struct cache_file *cache;
static struct cache_file_new *cache_new;
static size_t cachesize;
+#ifdef SHARED
+/* This is used to cache the priorities of glibc-hwcaps
+ subdirectories. The elements of _dl_cache_priorities correspond to
+ the strings in the cache_extension_tag_glibc_hwcaps section. */
+static uint32_t *glibc_hwcaps_priorities;
+static uint32_t glibc_hwcaps_priorities_length;
+static uint32_t glibc_hwcaps_priorities_allocated;
+
+/* True if the full malloc was used to allocated the array. */
+static bool glibc_hwcaps_priorities_malloced;
+
+/* Deallocate the glibc_hwcaps_priorities array. */
+static void
+glibc_hwcaps_priorities_free (void)
+{
+ /* When the minimal malloc is in use, free does not do anything,
+ so it does not make sense to call it. */
+ if (glibc_hwcaps_priorities_malloced)
+ free (glibc_hwcaps_priorities);
+ glibc_hwcaps_priorities = NULL;
+ glibc_hwcaps_priorities_allocated = 0;
+}
+
+/* Return the priority of the cache_extension_tag_glibc_hwcaps section
+ entry at INDEX. Zero means do not use. Otherwise, lower values
+ indicate greater preference. */
+static uint32_t __attribute__ ((noinline, noclone))
+glibc_hwcaps_priority (uint32_t index)
+{
+ /* Using a zero-length array as an indicator that nothing has been
+ loaded is not a problem: It does not lead to repeated
+ initialization attempts because caches without an extension
+ section are processed without calling this function (unless the
+ file is corrupted). */
+ if (glibc_hwcaps_priorities_length == 0)
+ {
+ struct cache_extension_all_loaded ext;
+ if (!cache_extension_load (cache_new, cache, cachesize, &ext))
+ return 0;
+
+ uint32_t length
+ = (ext.sections[cache_extension_tag_glibc_hwcaps].size
+ / sizeof (uint32_t));
+ if (length > glibc_hwcaps_priorities_allocated)
+ {
+ glibc_hwcaps_priorities_free ();
+
+ glibc_hwcaps_priorities = malloc (length * sizeof (uint32_t));
+ if (glibc_hwcaps_priorities == NULL)
+ /* Disable hwcaps on memory allocation error. */
+ return 0;
+
+ glibc_hwcaps_priorities_allocated = length;
+ glibc_hwcaps_priorities_malloced = __rtld_malloc_is_full ();
+ }
+
+ /* Compute the priorities for the subdirectories by merging the
+ array in the cache with the dl_hwcaps_priorities array. */
+ const uint32_t *left
+ = ext.sections[cache_extension_tag_glibc_hwcaps].base;
+ const uint32_t *left_end = left + length;
+ struct dl_hwcaps_priority *right = _dl_hwcaps_priorities;
+ struct dl_hwcaps_priority *right_end
+ = right + _dl_hwcaps_priorities_length;
+ uint32_t *result = glibc_hwcaps_priorities;
+
+ while (left < left_end && right < right_end)
+ {
+ uint32_t string_table_index = *left;
+ if (string_table_index < cachesize)
+ {
+ const char *left_name
+ = (const char *) cache + string_table_index;
+ uint32_t left_name_length = strlen (left_name);
+ uint32_t to_compare;
+ if (left_name_length < right->name_length)
+ to_compare = left_name_length;
+ else
+ to_compare = right->name_length;
+ int cmp = memcmp (left_name, right->name, to_compare);
+ if (cmp == 0)
+ {
+ if (left_name_length < right->name_length)
+ cmp = -1;
+ else if (left_name_length > right->name_length)
+ cmp = 1;
+ }
+ if (cmp == 0)
+ {
+ *result = right->priority;
+ ++result;
+ ++left;
+ ++right;
+ }
+ else if (cmp < 0)
+ {
+ *result = 0;
+ ++result;
+ ++left;
+ }
+ else
+ ++right;
+ }
+ else
+ {
+ *result = 0;
+ ++result;
+ }
+ }
+ while (left < left_end)
+ {
+ *result = 0;
+ ++result;
+ ++left;
+ }
+
+ glibc_hwcaps_priorities_length = length;
+ }
+
+ if (index < glibc_hwcaps_priorities_length)
+ return glibc_hwcaps_priorities[index];
+ else
+ return 0;
+}
+#endif /* SHARED */
+
/* True if PTR is a valid string table index. */
static inline bool
_dl_cache_verify_ptr (uint32_t ptr, size_t string_table_size)
@@ -74,6 +200,9 @@ search_cache (const char *string_table, uint32_t string_table_size,
int left = 0;
int right = nlibs - 1;
const char *best = NULL;
+#ifdef SHARED
+ uint32_t best_priority = 0;
+#endif
while (left <= right)
{
@@ -129,6 +258,11 @@ search_cache (const char *string_table, uint32_t string_table_size,
{
if (best == NULL || flags == GLRO (dl_correct_cache_id))
{
+ /* Named/extension hwcaps get slightly different
+ treatment: We keep searching for a better
+ match. */
+ bool named_hwcap = false;
+
if (entry_size >= sizeof (struct file_entry_new))
{
/* The entry is large enough to include
@@ -136,7 +270,18 @@ search_cache (const char *string_table, uint32_t string_table_size,
struct file_entry_new *libnew
= (struct file_entry_new *) lib;
- if (libnew->hwcap & hwcap_exclude)
+#ifdef SHARED
+ named_hwcap = dl_cache_hwcap_extension (libnew);
+#endif
+
+ /* The entries with named/extension hwcaps
+ have been exhausted. Return the best
+ match encountered so far if there is
+ one. */
+ if (!named_hwcap && best != NULL)
+ break;
+
+ if ((libnew->hwcap & hwcap_exclude) && !named_hwcap)
continue;
if (GLRO (dl_osversion)
&& libnew->osversion > GLRO (dl_osversion))
@@ -146,14 +291,41 @@ search_cache (const char *string_table, uint32_t string_table_size,
&& ((libnew->hwcap & _DL_HWCAP_PLATFORM)
!= platform))
continue;
+
+#ifdef SHARED
+ /* For named hwcaps, determine the priority
+ and see if beats what has been found so
+ far. */
+ if (named_hwcap)
+ {
+ uint32_t entry_priority
+ = glibc_hwcaps_priority (libnew->hwcap);
+ if (entry_priority == 0)
+ /* Not usable at all. Skip. */
+ continue;
+ else if (best == NULL
+ || entry_priority < best_priority)
+ /* This entry is of higher priority
+ than the previous one, or it is the
+ first entry. */
+ best_priority = entry_priority;
+ else
+ /* An entry has already been found,
+ but it is a better match. */
+ continue;
+ }
+#endif /* SHARED */
}
best = string_table + lib->value;
- if (flags == GLRO (dl_correct_cache_id))
+ if (flags == GLRO (dl_correct_cache_id)
+ && !named_hwcap)
/* We've found an exact match for the shared
object and no general `ELF' release. Stop
- searching. */
+ searching, but not if a named (extension)
+ hwcap is used. In this case, an entry with
+ a higher priority may come up later. */
break;
}
}
@@ -346,5 +518,9 @@ _dl_unload_cache (void)
__munmap (cache, cachesize);
cache = NULL;
}
+#ifdef SHARED
+ /* This marks the glibc_hwcaps_priorities array as out-of-date. */
+ glibc_hwcaps_priorities_length = 0;
+#endif
}
#endif
@@ -89,6 +89,81 @@ copy_hwcaps (struct copy_hwcaps *target, const char *hwcaps,
}
}
+struct dl_hwcaps_priority *_dl_hwcaps_priorities;
+uint32_t _dl_hwcaps_priorities_length;
+
+/* Allocate _dl_hwcaps_priorities and fill it with data. */
+static void
+compute_priorities (size_t total_count, const char *prepend,
+ int32_t bitmask, const char *mask)
+{
+ _dl_hwcaps_priorities = malloc (total_count
+ * sizeof (*_dl_hwcaps_priorities));
+ if (_dl_hwcaps_priorities == NULL)
+ _dl_signal_error (ENOMEM, NULL, NULL,
+ N_("cannot create HWCAP priorities"));
+ _dl_hwcaps_priorities_length = total_count;
+
+ /* First the prepended subdirectories. */
+ size_t i = 0;
+ {
+ struct dl_hwcaps_split sp;
+ _dl_hwcaps_split_init (&sp, prepend);
+ while (_dl_hwcaps_split (&sp))
+ {
+ _dl_hwcaps_priorities[i].name = sp.segment;
+ _dl_hwcaps_priorities[i].name_length = sp.length;
+ _dl_hwcaps_priorities[i].priority = i + 1;
+ ++i;
+ }
+ }
+
+ /* Then the built-in subdirectories that are actually active. */
+ {
+ struct dl_hwcaps_split_masked sp;
+ _dl_hwcaps_split_masked_init (&sp, _dl_hwcaps_subdirs, bitmask, mask);
+ while (_dl_hwcaps_split_masked (&sp))
+ {
+ _dl_hwcaps_priorities[i].name = sp.split.segment;
+ _dl_hwcaps_priorities[i].name_length = sp.split.length;
+ _dl_hwcaps_priorities[i].priority = i + 1;
+ ++i;
+ }
+ }
+ assert (i == total_count);
+}
+
+/* Sort the _dl_hwcaps_priorities array by name. */
+static void
+sort_priorities_by_name (void)
+{
+ /* Insertion sort. There is no need to link qsort into the dynamic
+ loader for such a short array. */
+ for (size_t i = 1; i < _dl_hwcaps_priorities_length; ++i)
+ for (size_t j = i; j > 0; --j)
+ {
+ struct dl_hwcaps_priority *previous = _dl_hwcaps_priorities + j - 1;
+ struct dl_hwcaps_priority *current = _dl_hwcaps_priorities + j;
+
+ /* Bail out if current is greater or equal to the previous
+ value. */
+ uint32_t to_compare;
+ if (current->name_length < previous->name_length)
+ to_compare = current->name_length;
+ else
+ to_compare = previous->name_length;
+ int cmp = memcmp (current->name, previous->name, to_compare);
+ if (cmp >= 0
+ || (cmp == 0 && current->name_length >= previous->name_length))
+ break;
+
+ /* Swap *previous and *current. */
+ struct dl_hwcaps_priority tmp = *previous;
+ *previous = *current;
+ *current = tmp;
+ }
+}
+
/* Return an array of useful/necessary hardware capability names. */
const struct r_strlenpair *
_dl_important_hwcaps (const char *glibc_hwcaps_prepend,
@@ -111,6 +186,9 @@ _dl_important_hwcaps (const char *glibc_hwcaps_prepend,
count_hwcaps (&hwcaps_counts, glibc_hwcaps_prepend, -1, NULL);
count_hwcaps (&hwcaps_counts, _dl_hwcaps_subdirs, hwcaps_subdirs_active,
glibc_hwcaps_mask);
+ compute_priorities (hwcaps_counts.count, glibc_hwcaps_prepend,
+ hwcaps_subdirs_active, glibc_hwcaps_mask);
+ sort_priorities_by_name ();
/* Each hwcaps subdirectory has a GLIBC_HWCAPS_PREFIX string prefix
and a "/" suffix once stored in the result. */
@@ -110,4 +110,23 @@ extern const char _dl_hwcaps_subdirs[] attribute_hidden;
bitmask. */
int32_t _dl_hwcaps_subdirs_active (void) attribute_hidden;
+/* Pre-computed glibc-hwcaps subdirectory priorities. Used in
+ dl-cache.c to quickly find the proprities for the stored HWCAP
+ names. */
+struct dl_hwcaps_priority
+{
+ /* The name consists of name_length bytes at name (not necessarily
+ null-terminated). */
+ const char *name;
+ uint32_t name_length;
+
+ /* Priority of this name. A positive number. */
+ uint32_t priority;
+};
+
+/* Pre-computed hwcaps priorities. Set up by
+ _dl_important_hwcaps. */
+extern struct dl_hwcaps_priority *_dl_hwcaps_priorities attribute_hidden;
+extern uint32_t _dl_hwcaps_priorities_length attribute_hidden;
+
#endif /* _DL_HWCAPS_H */